Improvement in screw-drivers



F. B. HUNT.

Screw-Drivers.

Patentedjaq. 28,1873.

Fig.1

UNITED STATES PATENT OFFICE FRANKLIN B. HUNT, OF RICHMOND, INDIANA,ASSIGN OR TO EDWARD R. MATTHEWS AND WILLIAM N. MATTHEWS, OF SAME PLACE.

IMPROVEMENT IN SCREW-DRIVERS. v

Specification forming part of Letters Patent No. 135,340, dated January28, 1873.

11d of the levers or jaws against the plunger Fig. 3 is a view of theplunger. Fig. 4 is a view of one of the jaws. I

In making the chuck, I first prepare the body or barrel A by boring thehole for the plunger B and planing grooves 0 in the sides of the barrelto receive the jaws C. There is a projection on the lower end of thebarrel, shown at H, through which the jaws pass, and

7 also a pin, 6, upon which the jaws vibrate, the

pin 0 being the fulcrum of the lever, formed by extending the jawsupward. The upper end of the plunger B is made cone-shape, and the lowerend, K, is made a little smaller than thescrew or article which isintended tobe grasped and held. The spring-band I being placed in therecesses L in the upper end of the jaws or levers holds them inward onthe cone at the upper end of the plunger B, and

opens the jaws at their lower extremities. The shank E is placed in asocket to fit, which may be worked by hand or power, and the whole thingis revolved. 3

Thus it will be seen that when the whole machine is pressed'down uponthe top of the screw, as shown at G, Fig. 1, the lower end of theplunger comes in contact with the upper end of the screw, and is therebyforced upward, and the upper tapering end of the plunger B is forcedbetween the upper inclined ends of the jaws, as shown at S,'pressingthem outwardly, and consequently the lower ends inwardly, to grasp thescrew. I thus combine two forces; the lever formed by the jaws and theinclined plane of the upper end of the plunger. In place of thespring-band I, sepa rate springs may be attached to the upper end of thebarrel, which will press upon the upper end of the levers or jaws O,fand keep them in place when the machine is at rest.

Any suitable attachment of spring or springs for this purpose may beused.

What I claim, and desire to secure by Letters Patent, is

The combination of the barrel A, jaws O, plunger B, and spring-band 1,when operating in the manner and for the purpose substau tiall y asdescribed.

FRANKLIN B. HUNT.

Witnesses:

NELsoN A. HUNT, WM. N. MATTHEWS.

